Photo by U.S. Fish and Wildlife Service
One of the most iconic butterfly species, the black and orange monarch, will embark on a massive 3,000-mile migration in September.The monarch migration will travel through Nebraska, but not as many monarchs will be making the journey as in years past.
At their peak population in 1996, 1 billion butterflies migrated through the eastern two-thirds of the United States to a small 50-acre forest in Mexico to escape the Midwest winter.
Four years ago, the monarch butterfly population had declined by 70% to 30 million, although last year the population increased by 150 million, according to Dr. Theodore Burk, a Creighton University entomologist who has been studying monarchs for nearly two decades.
Burk says changes in American agriculture has had a negative impact on the monarch species. In the past 20 years, half of the monarchs’ food base has been eliminated.
“The monarchs’ primary food source is milkweed, which is prevalent in Nebraska and across the corn belt in the Midwest,” Burk said. “Farmers are using pesticides and nicotine-based insecticides to protect their crops, and that can significantly reduce milkweed plants and cause harm to pollinator insects.”
Monarchs also use milkweed plants to lay their eggs, since larvae and caterpillars can only feed on milkweed, which provides monarchs with toxins to ward off predators. Also, a decrease in flowers that contain nectar could be another factor that hurts the monarch butterfly.
During monarchs’ migration to Mexico, they feed on thistle flowers to get them through the winter, however, some species of thistle are considered noxious weeds that are required to be removed by law.
Deforestation near Mexico City also is having a negative impact on the butterflies. Monarchs require a cool area to live in, but the narrow bands of forest where monarchs ride out the winter and breed have also been subjected to widespread and illegal logging operations.
“Half of the monarchs that migrated to Mexico last year were killed in an ice storm,” Burk said. “Monarchs are cold-blooded and are protected from the cold if they are dry. Some monarchs are being forced to live on the edges of forests, where there are not as many trees, and that can cause some of them to freeze.”
Monarchs and other pollinator insects are not considered a threatened or endangered species; however, they are deemed to be at risk.
In Nebraska, the Nebraska Game and Parks Commission is hoping to plant millions of milkweed species across the state over the next three years. Planting milkweed and other plants also can help conserve other pollinator insects.
“While our lives wouldn’t be affected dramatically if the monarchs went extinct, they are representatives for all flies, wasps, beetles and bees that are critical to our native existence and food supply,” Burk said. “They are also fascinating to look at and are the only insects to make this phenomenal migration.”
Burk has been researching monarchs since 1998. He visits Glacier Creek Preserve, a tallgrass prairie northwest of Omaha, 20 weeks out of the year to document monarchs and the plants they favor. Creighton University in Omaha enrolls 4,100 undergraduates and 4,200 graduate and professional students among nine schools and colleges.
No other university its size offers students such a comprehensive academic environment with personal attention from faculty-mentors. Jesuit and Catholic, it affords incomparable inter-professional education, bridging eight health profession programs with law, business and the arts and sciences – all on one walkable campus.